Is Kate Middleton not a fan of Prince Harry's girlfriend Cressida Bonas? Recent rumors have been surfacing that Prince Harry may become engaged to Cressida Bonas by the end of this year, and some insiders are saying Kate Middleton, Prince Harry's sister-in-law, is not too pleased with his choice of girlfriend.

"Cressida has said Kate is not keen on her relationship with Harry," an insider told The Telegraph, Entertainmentwise.com reports.

According to the report, the reason behind Kate's animosity towards Cressida is Prince William's past. It's been said that Prince William, Kate Middleton's husband, once had a crush on Cressida's half-sister Isabella. Though Isabella is now married to Richard Branson's son Sam, Kate hasn't got over it, Entertainmentwise.com reports.

"Cressie and Isabella could not be closer. Where she goes, Bella goes," the source said.

"Kate does not like Isabella because William loved her, and that caused their break-up. Bella's treatment at the royal wedding won't be forgotten," the source added.

The insider was referring to the royal wedding in 2011 between William and Kate, in which Cressida and Isabella were only invited to the service at Westminster Abbey, and not to either of the two receptions, but instead were taken home before lunch, WeWomen.com reports.

According to the website, a source recently told The Daily Star: "The way it's looking now people close to Harry and Cressida predict an engagement by the end of the year and a spring wedding.

"Cressida is The One. He's so close to her. All the tell-tale signs are there.

"People have heard Harry talking about how special Cress is and about getting engaged.

The insider insisted: "He is taking a lot of time and trouble to devote so much time to her and see her as often as he can. This romance is different.

"She is the special one. Everyone who knows them is saying that.

"Unless they have some major bust-up, the engagement will be this year."

If the reports are true, it looks like Kate Middleton better put her past grievances aside and welcome her potential new sister-in-law into the family.